16292

The observed rest-frame ultraviolet luminosity function (UV LF) of star-forming galaxies at z > 6 suggests that numerous low mass galaxies were responsible for reionizing the Universe by zvirgul6. In the current reionization models comma however comma the required escape fraction of ionizing photons (fesc) significantly depends on the faint-end limiting magnitude of the UV LF. Unfortunately comma there are no observational constraints on fesc in this UV-faint regime all galaxies with fesc measurements are brighter than Muv = -16. Thus comma constraining fesc for galaxies around the fiducial limiting magnitude (Muv = -13) are crucial to understand the role of faint galaxies in cosmic reionization comma but they are too faint to be observed at z > 7 even with JWST. We propose to obtain multi-wavelength HST imaging of two nearby comma metal-poor starburst dwarf galaxies (UGC 8091 and UGCA 292) that are fainter than Muv = -13. With these observations comma we willdoublePoint (1) measure the global escape fraction for galaxies below the limiting magnitude for the first time using their resolved stars (2) map the local escape fraction in each galaxy and (3) explore the relation between local escape fraction and physical environments. Establishing the relationships between local escape fraction and physical properties will greatly improve our understanding on the mechanisms for escape of ionizing photons. Furthermore comma those relationships can be used to infer the escape fractions of high-z galaxies that can not be resolved comma but with measured physical galactic properties. As a pilot program comma we will pave the way to probe the contribution of extreme UV-faint dwarf galaxies to cosmic reionization.